Hello <span>Mr1guy24
Question: </span><span>Radioactive isotopes are used to?
Answer: Determine the absolute age of rocks (A)
Reason: If we want to know the absolute age of rocks, then we use radioactive isotopes to find this out.
Hope This Helps!
-Chris</span>
For the first won is d the answerd
The incline is frictionless, this means we can use the conservation of energy: the initial kinetic energy of the block
is converted into gravitational potential energy
where h is the height reached by the block as it stops. By equalizing the two formulas, we get
However, this is the maximum height reached by the block. The distance along the surface of the plane is given by:
Physical changes: breaking sticks, boiling the water
chemical changes: lighting the fire
(Breaking the wood does not change the substance of the wood , therefore it's a physical change. Water changing between solid, liquid, and gas form is always a physical change.)
At its maximum height h, the football has zero vertical velocity, so if it was kicked with initial upward speed v, then
0² - v² = -2gh
Solve this for v :
v² = 2gh
v = √(2gh)
The height y of the football t seconds after being kicked is
y = vt - 1/2 gt²
Substitute v = √(2gh), replace y = h, and solve for h when t = 3.8 s :
h = √(2gh) t - 1/2 gt²
h = √(2gh) (3.8 s) - 1/2 g (3.8 s)²
h ≈ (16.8233 √m) √h - 70.756 m
(By √m, I mean "square root meters"; on its own this quantity doesn't make much physical sense, but we need this to be consistent with √h. h is measured in meters, so √h is measured in √m, too.)
h - (16.8233 √m) √h + 70.756 m = 0
Use the quadratic formula to solve for √h :
√h = ((16.8233 √m) ± √((16.8233 √m)² - 4 (70.756 m))) / 2
Both the positive and negative square roots result in the same solution,
√h ≈ 8.411 √m
Take the square of both sides to solve for h itself:
(√h)² ≈ (8.411 √m)²
⇒ h ≈ 70.756 m ≈ 71 m